1. Field of the Invention
This invention relates generally to the lumber handling art and more particularly to a method and apparatus for longitudinally conveying a pair of sector shaped pieces of wood.
2. Description of the Prior Art
The lumber manufacturing process has traditionally taken cylindrically shaped logs and broken them down into generally elongated rectangular pieces of lumber. Longitudinal sawing of logs into such shapes has been taking place for centuries, however, now with the supply of larger old growth logs being rapidly depleted it has become necessary to convert ever increasing numbers of smaller logs into lumber products. Smaller logs, as is well known, yield considerably less lumber on a volumetric basis and several new methods for increasing yields of smaller logs have been devised. Not only is the problem with generally lower yields important, it is also apparent that the flexibility in supplying needed products over the size range now available is limited. For example, with traditional longitudinal rectangular sawing it is impossible to cut a typical 2.times.10 piece of solid lumber from an eight inch diameter log.
Among various alternative lumber producing processes that would impact on the above-mentioned problems is one where logs are cut radially into a plurality of sector shaped pieces with two appropriately sized sectors then being rejoined such that the thin edge of one is approximately adjacent the thick edge of the other. The resulting pair can then be machined into usable shapes as lumber products or for edge gluing into wider widths. This process is fully disclosed in the issued U.S. Pat. No. 3,961,654 entitled `Log Cutting and Rejoining Process` and which is assigned to the assignee of the present invention. Another similar process is disclosed in the issued U.S. Pat. No. 3,903,943, also assigned to the assignee of the present invention. The disclosure in each is incorporated herein by this reference in order to offer one skilled in the art additional information with regard to the background and description of the present invention.
In each of the above-referenced inventive processes, a pair of elongated similarly sized sector shaped pieces can be rejoined along opposed faces in order to form a quadrilateral shape. Throughout the various process steps the sector shaped pieces must be handled and then transported between processing stations. It was determined that after the two sector shaped pieces to be joined had been selected, it would then be desirable to convey them as a pair. One convenient place in the process to begin conveying as pairs is where the sector shaped pieces come from the drying station. By way of explanation, the freshly cut green sector shaped pieces are dryed to a suitable moisture content prior to the bonding step. At this point in the process, or before, the two sectors to be adhesively bonded together are selected. According to the overall process the sectors are selected for size with a given size class normally being processed during a given operating period. The two selected sector shaped pieces are similar in size in that the smaller included angle of each is substantially the same, as will be their widths and lengths. As will be understood when referring to the aforementioned patents the widths of two sectors to be joined may vary, and this should be taken into account in any conveying process and machine. Also, while the included angles of the sector shaped pieces within a pair are similar, the included angle may vary between pairs of sectors. Thus, provision must be made to accommodate variable included angles of given sector pairs.